xref: /btstack/src/classic/avrcp_controller.c (revision d1207cd89697c74faa15e9ddc6cd0d1f10bfc4fa)
1 /*
2  * Copyright (C) 2016 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
24  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define __BTSTACK_FILE__ "avrcp_controller.c"
39 
40 #include <stdint.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <inttypes.h>
45 
46 #include "btstack.h"
47 #include "classic/avrcp.h"
48 #include "classic/avrcp_controller.h"
49 
50 static avrcp_context_t avrcp_controller_context;
51 
52 void avrcp_controller_create_sdp_record(uint8_t * service, uint32_t service_record_handle, uint8_t browsing, uint16_t supported_features, const char * service_name, const char * service_provider_name){
53     avrcp_create_sdp_record(1, service, service_record_handle, browsing, supported_features, service_name, service_provider_name);
54 }
55 
56 static void avrcp_emit_repeat_and_shuffle_mode(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t ctype, avrcp_repeat_mode_t repeat_mode, avrcp_shuffle_mode_t shuffle_mode){
57     if (!callback) return;
58     uint8_t event[8];
59     int pos = 0;
60     event[pos++] = HCI_EVENT_AVRCP_META;
61     event[pos++] = sizeof(event) - 2;
62     event[pos++] = AVRCP_SUBEVENT_SHUFFLE_AND_REPEAT_MODE;
63     little_endian_store_16(event, pos, avrcp_cid);
64     pos += 2;
65     event[pos++] = ctype;
66     event[pos++] = repeat_mode;
67     event[pos++] = shuffle_mode;
68     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
69 }
70 
71 static void avrcp_emit_operation_status(btstack_packet_handler_t callback, uint8_t subevent, uint16_t avrcp_cid, uint8_t ctype, uint8_t operation_id){
72     if (!callback) return;
73     uint8_t event[7];
74     int pos = 0;
75     event[pos++] = HCI_EVENT_AVRCP_META;
76     event[pos++] = sizeof(event) - 2;
77     event[pos++] = subevent;
78     little_endian_store_16(event, pos, avrcp_cid);
79     pos += 2;
80     event[pos++] = ctype;
81     event[pos++] = operation_id;
82     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
83 }
84 
85 static void avrcp_press_and_hold_timeout_handler(btstack_timer_source_t * timer){
86     UNUSED(timer);
87     avrcp_connection_t * connection = btstack_run_loop_get_timer_context(timer);
88     btstack_run_loop_set_timer(&connection->press_and_hold_cmd_timer, 2000); // 2 seconds timeout
89     btstack_run_loop_add_timer(&connection->press_and_hold_cmd_timer);
90     connection->state = AVCTP_W2_SEND_PRESS_COMMAND;
91     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
92 }
93 
94 static void avrcp_press_and_hold_timer_start(avrcp_connection_t * connection){
95     btstack_run_loop_remove_timer(&connection->press_and_hold_cmd_timer);
96     btstack_run_loop_set_timer_handler(&connection->press_and_hold_cmd_timer, avrcp_press_and_hold_timeout_handler);
97     btstack_run_loop_set_timer_context(&connection->press_and_hold_cmd_timer, connection);
98     btstack_run_loop_set_timer(&connection->press_and_hold_cmd_timer, 2000); // 2 seconds timeout
99     btstack_run_loop_add_timer(&connection->press_and_hold_cmd_timer);
100 }
101 
102 static void avrcp_press_and_hold_timer_stop(avrcp_connection_t * connection){
103     connection->continuous_fast_forward_cmd = 0;
104     btstack_run_loop_remove_timer(&connection->press_and_hold_cmd_timer);
105 }
106 
107 static uint8_t request_pass_through_release_control_cmd(avrcp_connection_t * connection){
108     connection->state = AVCTP_W2_SEND_RELEASE_COMMAND;
109     if (connection->continuous_fast_forward_cmd){
110         avrcp_press_and_hold_timer_stop(connection);
111     }
112     connection->cmd_operands[0] = 0x80 | connection->cmd_operands[0];
113     connection->transaction_label++;
114     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
115     return ERROR_CODE_SUCCESS;
116 }
117 
118 static inline uint8_t request_pass_through_press_control_cmd(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint16_t playback_speed, uint8_t continuous_fast_forward_cmd, avrcp_context_t * context){
119     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, context);
120     if (!connection){
121         log_error("avrcp: could not find a connection.");
122         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
123     }
124     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
125     connection->state = AVCTP_W2_SEND_PRESS_COMMAND;
126     connection->command_opcode =  AVRCP_CMD_OPCODE_PASS_THROUGH;
127     connection->command_type = AVRCP_CTYPE_CONTROL;
128     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
129     connection->subunit_id =   AVRCP_SUBUNIT_ID;
130     connection->cmd_operands_length = 0;
131 
132     connection->continuous_fast_forward_cmd = continuous_fast_forward_cmd;
133     connection->cmd_operands_length = 2;
134     connection->cmd_operands[0] = opid;
135     if (playback_speed > 0){
136         connection->cmd_operands[2] = playback_speed;
137         connection->cmd_operands_length++;
138     }
139     connection->cmd_operands[1] = connection->cmd_operands_length - 2;
140 
141     if (connection->continuous_fast_forward_cmd){
142         avrcp_press_and_hold_timer_start(connection);
143     }
144 
145     connection->transaction_label++;
146     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
147     return ERROR_CODE_SUCCESS;
148 }
149 
150 static uint8_t request_single_pass_through_press_control_cmd(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint16_t playback_speed){
151     return request_pass_through_press_control_cmd(avrcp_cid, opid, playback_speed, 0, &avrcp_controller_context);
152 }
153 
154 static uint8_t request_continuous_pass_through_press_control_cmd(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint16_t playback_speed){
155     return request_pass_through_press_control_cmd(avrcp_cid, opid, playback_speed, 1, &avrcp_controller_context);
156 }
157 
158 static int avrcp_send_cmd(uint16_t cid, avrcp_connection_t * connection){
159     uint8_t command[30];
160     int pos = 0;
161     // transport header
162     // Transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
163     command[pos++] = (connection->transaction_label << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_COMMAND_FRAME << 1) | 0;
164     // Profile IDentifier (PID)
165     command[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
166     command[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
167 
168     // command_type
169     command[pos++] = connection->command_type;
170     // subunit_type | subunit ID
171     command[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
172     // opcode
173     command[pos++] = (uint8_t)connection->command_opcode;
174     // operands
175     memcpy(command+pos, connection->cmd_operands, connection->cmd_operands_length);
176     pos += connection->cmd_operands_length;
177 
178     return l2cap_send(cid, command, pos);
179 }
180 
181 static int avrcp_register_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t event_id){
182     if (connection->notifications_to_deregister & (1 << event_id)) return 0;
183     if (connection->notifications_enabled & (1 << event_id)) return 0;
184     if (connection->notifications_to_register & (1 << event_id)) return 0;
185     connection->notifications_to_register |= (1 << event_id);
186     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
187     return 1;
188 }
189 
190 static void avrcp_prepare_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t event_id){
191     connection->transaction_label++;
192     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
193     connection->command_type = AVRCP_CTYPE_NOTIFY;
194     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
195     connection->subunit_id = AVRCP_SUBUNIT_ID;
196     int pos = 0;
197     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
198     pos += 3;
199     connection->cmd_operands[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
200     connection->cmd_operands[pos++] = 0;                     // reserved(upper 6) | packet_type -> 0
201     big_endian_store_16(connection->cmd_operands, pos, 5);     // parameter length
202     pos += 2;
203     connection->cmd_operands[pos++] = event_id;
204     big_endian_store_32(connection->cmd_operands, pos, 0);
205     pos += 4;
206     connection->cmd_operands_length = pos;
207     // AVRCP_SPEC_V14.pdf 166
208     // answer page 61
209 }
210 
211 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t *packet, uint16_t size){
212     uint8_t operands[20];
213     uint8_t opcode;
214     int     pos = 3;
215     // uint8_t transport_header = packet[0];
216     // uint8_t transaction_label = transport_header >> 4;
217     // uint8_t packet_type = (transport_header & 0x0F) >> 2;
218     // uint8_t frame_type = (transport_header & 0x03) >> 1;
219     // uint8_t ipid = transport_header & 0x01;
220     // uint8_t byte_value = packet[2];
221     // uint16_t pid = (byte_value << 8) | packet[2];
222 
223     avrcp_command_type_t ctype = (avrcp_command_type_t) packet[pos++];
224     uint8_t byte_value = packet[pos++];
225     avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (byte_value >> 3);
226     avrcp_subunit_type_t subunit_id = (avrcp_subunit_type_t)   (byte_value & 0x07);
227     opcode = packet[pos++];
228 
229     // printf("    Transport header 0x%02x (transaction_label %d, packet_type %d, frame_type %d, ipid %d), pid 0x%4x\n",
230     //     transport_header, transaction_label, packet_type, frame_type, ipid, pid);
231     // // printf_hexdump(packet+pos, size-pos);
232 
233     uint8_t pdu_id;
234     uint16_t param_length;
235     switch (avrcp_cmd_opcode(packet,size)){
236         case AVRCP_CMD_OPCODE_UNIT_INFO:{
237             if (connection->state != AVCTP_W2_RECEIVE_RESPONSE) return;
238             connection->state = AVCTP_CONNECTION_OPENED;
239 
240             // operands:
241             memcpy(operands, packet+pos, 5);
242             uint8_t unit_type = operands[1] >> 3;
243             uint8_t unit = operands[1] & 0x07;
244             uint32_t company_id = operands[2] << 16 | operands[3] << 8 | operands[4];
245             log_info("    UNIT INFO response: ctype 0x%02x (0C), subunit_type 0x%02x (1F), subunit_id 0x%02x (07), opcode 0x%02x (30), unit_type 0x%02x, unit %d, company_id 0x%06" PRIx32,
246                 ctype, subunit_type, subunit_id, opcode, unit_type, unit, company_id );
247             break;
248         }
249         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
250             if (size - pos < 7) {
251                 log_error("avrcp: wrong packet size");
252                 return;
253             };
254             // operands:
255             memcpy(operands, packet+pos, 7);
256             pos += 7;
257             // uint32_t company_id = operands[0] << 16 | operands[1] << 8 | operands[2];
258             pdu_id = operands[3];
259 
260             if (connection->state != AVCTP_W2_RECEIVE_RESPONSE && pdu_id != AVRCP_PDU_ID_REGISTER_NOTIFICATION){
261                 log_info("AVRCP_CMD_OPCODE_VENDOR_DEPENDENT state %d", connection->state);
262                 return;
263             }
264             connection->state = AVCTP_CONNECTION_OPENED;
265 
266 
267             // uint8_t unit_type = operands[4] >> 3;
268             // uint8_t unit = operands[4] & 0x07;
269             param_length = big_endian_read_16(operands, 5);
270 
271             // printf("    VENDOR DEPENDENT response: ctype 0x%02x (0C), subunit_type 0x%02x (1F), subunit_id 0x%02x (07), opcode 0x%02x (30), unit_type 0x%02x, unit %d, company_id 0x%06x\n",
272             //     ctype, subunit_type, subunit_id, opcode, unit_type, unit, company_id );
273 
274             // if (ctype == AVRCP_CTYPE_RESPONSE_INTERIM) return;
275             log_info("        VENDOR DEPENDENT response: pdu id 0x%02x, param_length %d, status %s", pdu_id, param_length, avrcp_ctype2str(ctype));
276             switch (pdu_id){
277                 case AVRCP_PDU_ID_GetCurrentPlayerApplicationSettingValue:{
278                     uint8_t num_attributes = packet[pos++];
279                     int i;
280                     avrcp_repeat_mode_t  repeat_mode =  AVRCP_REPEAT_MODE_INVALID;
281                     avrcp_shuffle_mode_t shuffle_mode = AVRCP_SHUFFLE_MODE_INVALID;
282                     for (i = 0; i < num_attributes; i++){
283                         uint8_t attribute_id    = packet[pos++];
284                         uint8_t value = packet[pos++];
285                         switch (attribute_id){
286                             case 0x02:
287                                 repeat_mode = (avrcp_repeat_mode_t) value;
288                                 break;
289                             case 0x03:
290                                 shuffle_mode = (avrcp_shuffle_mode_t) value;
291                                 break;
292                             default:
293                                 break;
294                         }
295                     }
296                     avrcp_emit_repeat_and_shuffle_mode(avrcp_controller_context.avrcp_callback, connection->avrcp_cid, ctype, repeat_mode, shuffle_mode);
297                     break;
298                 }
299                 case AVRCP_PDU_ID_SetPlayerApplicationSettingValue:{
300                     uint8_t event[6];
301                     int offset = 0;
302                     event[offset++] = HCI_EVENT_AVRCP_META;
303                     event[offset++] = sizeof(event) - 2;
304                     event[offset++] = AVRCP_SUBEVENT_PLAYER_APPLICATION_VALUE_RESPONSE;
305                     little_endian_store_16(event, offset, connection->avrcp_cid);
306                     offset += 2;
307                     event[offset++] = ctype;
308                     (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
309                     break;
310                 }
311                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME:{
312                     uint8_t event[7];
313                     int offset = 0;
314                     event[offset++] = HCI_EVENT_AVRCP_META;
315                     event[offset++] = sizeof(event) - 2;
316                     event[offset++] = AVRCP_SUBEVENT_SET_ABSOLUTE_VOLUME_RESPONSE;
317                     little_endian_store_16(event, offset, connection->avrcp_cid);
318                     offset += 2;
319                     event[offset++] = ctype;
320                     event[offset++] = packet[pos++];
321                     (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
322                     break;
323                 }
324                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
325                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) packet[pos++];
326                     uint8_t capability_count = packet[pos++];
327                     int i;
328                     switch (capability_id){
329                         case AVRCP_CAPABILITY_ID_COMPANY:
330                             // log_info("Supported companies %d: ", capability_count);
331                             for (i = 0; i < capability_count; i++){
332                                 uint32_t company_id = big_endian_read_24(packet, pos);
333                                 pos += 3;
334                                 log_info("  0x%06" PRIx32 ", ", company_id);
335                             }
336                             break;
337                         case AVRCP_CAPABILITY_ID_EVENT:
338                             // log_info("Supported events %d: ", capability_count);
339                             for (i = 0; i < capability_count; i++){
340                                 uint8_t event_id = packet[pos++];
341                                 log_info("  0x%02x %s", event_id, avrcp_event2str(event_id));
342                             }
343                             break;
344                     }
345                     break;
346                 }
347                 case AVRCP_PDU_ID_GET_PLAY_STATUS:{
348                     uint32_t song_length = big_endian_read_32(packet, pos);
349                     pos += 4;
350                     uint32_t song_position = big_endian_read_32(packet, pos);
351                     pos += 4;
352                     uint8_t play_status = packet[pos];
353                     // log_info("        GET_PLAY_STATUS length 0x%04X, position 0x%04X, status %s", song_length, song_position, avrcp_play_status2str(play_status));
354 
355                     uint8_t event[15];
356                     int offset = 0;
357                     event[offset++] = HCI_EVENT_AVRCP_META;
358                     event[offset++] = sizeof(event) - 2;
359                     event[offset++] = AVRCP_SUBEVENT_PLAY_STATUS;
360                     little_endian_store_16(event, offset, connection->avrcp_cid);
361                     offset += 2;
362                     event[offset++] = ctype;
363                     little_endian_store_32(event, offset, song_length);
364                     offset += 4;
365                     little_endian_store_32(event, offset, song_position);
366                     offset += 4;
367                     event[offset++] = play_status;
368                     (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
369                     break;
370                 }
371                 case AVRCP_PDU_ID_REGISTER_NOTIFICATION:{
372                     avrcp_notification_event_id_t  event_id = (avrcp_notification_event_id_t) packet[pos++];
373                     uint16_t event_mask = (1 << event_id);
374                     uint16_t reset_event_mask = ~event_mask;
375                     switch (ctype){
376                         case AVRCP_CTYPE_RESPONSE_INTERIM:
377                             // register as enabled
378                             connection->notifications_enabled |= event_mask;
379                             // printf("INTERIM notifications_enabled 0x%2x, notifications_to_register 0x%2x\n", connection->notifications_enabled,  connection->notifications_to_register);
380                             break;
381                         case AVRCP_CTYPE_RESPONSE_CHANGED_STABLE:
382                             // received change, event is considered deregistered
383                             // we are re-enabling it automatically, if it is not
384                             // explicitly disabled
385                             connection->notifications_enabled &= reset_event_mask;
386                             if (! (connection->notifications_to_deregister & event_mask)){
387                                 avrcp_register_notification(connection, event_id);
388                                 // printf("CHANGED_STABLE notifications_enabled 0x%2x, notifications_to_register 0x%2x\n", connection->notifications_enabled,  connection->notifications_to_register);
389                             } else {
390                                 connection->notifications_to_deregister &= reset_event_mask;
391                             }
392                             break;
393                         default:
394                             connection->notifications_to_register &= reset_event_mask;
395                             connection->notifications_enabled &= reset_event_mask;
396                             connection->notifications_to_deregister &= reset_event_mask;
397                             break;
398                     }
399 
400                     switch (event_id){
401                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:{
402                             uint8_t event[7];
403                             int offset = 0;
404                             event[offset++] = HCI_EVENT_AVRCP_META;
405                             event[offset++] = sizeof(event) - 2;
406                             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_PLAYBACK_STATUS_CHANGED;
407                             little_endian_store_16(event, offset, connection->avrcp_cid);
408                             offset += 2;
409                             event[offset++] = ctype;
410                             event[offset++] = packet[pos];
411                             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
412                             break;
413                         }
414                         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:{
415                             uint8_t event[6];
416                             int offset = 0;
417                             event[offset++] = HCI_EVENT_AVRCP_META;
418                             event[offset++] = sizeof(event) - 2;
419                             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_TRACK_CHANGED;
420                             little_endian_store_16(event, offset, connection->avrcp_cid);
421                             offset += 2;
422                             event[offset++] = ctype;
423                             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
424                             break;
425                         }
426                         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:{
427                             uint8_t event[6];
428                             int offset = 0;
429                             event[offset++] = HCI_EVENT_AVRCP_META;
430                             event[offset++] = sizeof(event) - 2;
431                             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_NOW_PLAYING_CONTENT_CHANGED;
432                             little_endian_store_16(event, offset, connection->avrcp_cid);
433                             offset += 2;
434                             event[offset++] = ctype;
435                             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
436                             break;
437                         }
438                         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:{
439                             uint8_t event[6];
440                             int offset = 0;
441                             event[offset++] = HCI_EVENT_AVRCP_META;
442                             event[offset++] = sizeof(event) - 2;
443                             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_AVAILABLE_PLAYERS_CHANGED;
444                             little_endian_store_16(event, offset, connection->avrcp_cid);
445                             offset += 2;
446                             event[offset++] = ctype;
447                             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
448                             break;
449                         }
450                         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:{
451                             uint8_t event[7];
452                             int offset = 0;
453                             event[offset++] = HCI_EVENT_AVRCP_META;
454                             event[offset++] = sizeof(event) - 2;
455                             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_VOLUME_CHANGED;
456                             little_endian_store_16(event, offset, connection->avrcp_cid);
457                             offset += 2;
458                             event[offset++] = ctype;
459                             event[offset++] = packet[pos++] & 0x7F;
460                             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
461                             break;
462                         }
463                         // case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:{
464                         //     uint8_t num_PlayerApplicationSettingAttributes = packet[pos++];
465                         //     int i;
466                         //     for (i = 0; i < num_PlayerApplicationSettingAttributes; i++){
467                         //         uint8_t PlayerApplicationSetting_AttributeID = packet[pos++];
468                         //         uint8_t PlayerApplicationSettingValueID = packet[pos++];
469                         //     }
470                         //     break;
471                         // }
472                         // case AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED:
473                         //     uint16_t player_id = big_endian_read_16(packet, pos);
474                         //     pos += 2;
475                         //     uint16_t uid_counter = big_endian_read_16(packet, pos);
476                         //     pos += 2;
477                         //     break;
478                         // case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:
479                         //     uint16_t uid_counter = big_endian_read_16(packet, pos);
480                         //     pos += 2;
481                         //     break;
482                         default:
483                             log_info("avrcp: not implemented");
484                             break;
485                     }
486                     if (connection->notifications_to_register != 0){
487                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
488                     }
489                     break;
490                 }
491 
492                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
493                     uint8_t num_attributes = packet[pos++];
494                     unsigned int i;
495                     struct item {
496                         uint16_t len;
497                         uint8_t  * value;
498                     } items[AVRCP_MEDIA_ATTR_COUNT];
499                     memset(items, 0, sizeof(items));
500 
501                     uint16_t string_attributes_len = 0;
502                     uint8_t  num_string_attributes = 0;
503                     uint16_t total_event_payload_for_string_attributes = HCI_EVENT_PAYLOAD_SIZE-2;
504                     uint16_t max_string_attribute_value_len = 0;
505                     if (ctype == AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE || ctype == AVRCP_CTYPE_RESPONSE_CHANGED_STABLE){
506                         for (i = 0; i < num_attributes; i++){
507                             // use local variables to avoid compiler warning
508                             uint32_t avrcp_media_attribute_id =  big_endian_read_32(packet, pos);
509                             avrcp_media_attribute_id_t attr_id = (avrcp_media_attribute_id_t) avrcp_media_attribute_id;
510                             pos += 4;
511                             // uint16_t character_set = big_endian_read_16(packet, pos);
512                             pos += 2;
513                             uint16_t attr_value_length = big_endian_read_16(packet, pos);
514                             pos += 2;
515 
516                             // debug - to remove later
517                             uint8_t  value[100];
518                             uint16_t value_len = sizeof(value) <= attr_value_length? sizeof(value) - 1 : attr_value_length;
519                             memcpy(value, packet+pos, value_len);
520                             value[value_len] = 0;
521                             // printf("Now Playing Info %s: %s \n", attribute2str(attr_id), value);
522                             // end debug
523 
524                             if ((attr_id >= 1) || (attr_id <= AVRCP_MEDIA_ATTR_COUNT)) {
525                                 items[attr_id-1].len = attr_value_length;
526                                 items[attr_id-1].value = &packet[pos];
527                                 switch (attr_id){
528                                     case AVRCP_MEDIA_ATTR_TITLE:
529                                     case AVRCP_MEDIA_ATTR_ARTIST:
530                                     case AVRCP_MEDIA_ATTR_ALBUM:
531                                     case AVRCP_MEDIA_ATTR_GENRE:
532                                         num_string_attributes++;
533                                         string_attributes_len += attr_value_length;
534                                         if (max_string_attribute_value_len < attr_value_length){
535                                             max_string_attribute_value_len = attr_value_length;
536                                         }
537                                         break;
538                                     default:
539                                         break;
540                                 }
541                             }
542                             pos += attr_value_length;
543                         }
544                     }
545 
546                     // subtract space for fixed fields
547                     total_event_payload_for_string_attributes -= 14 + 4;    // 4 for '\0'
548 
549                     // @TODO optimize space by repeatedly decreasing max_string_attribute_value_len until it fits into buffer instead of crude divion
550                     uint16_t max_value_len = total_event_payload_for_string_attributes > string_attributes_len? max_string_attribute_value_len : total_event_payload_for_string_attributes/(string_attributes_len+1) - 1;
551                     // printf("num_string_attributes %d, string_attributes_len %d, total_event_payload_for_string_attributes %d, max_value_len %d \n", num_string_attributes, string_attributes_len, total_event_payload_for_string_attributes, max_value_len);
552 
553                     const uint8_t attribute_order[] = {
554                         AVRCP_MEDIA_ATTR_TRACK,
555                         AVRCP_MEDIA_ATTR_TOTAL_TRACKS,
556                         AVRCP_MEDIA_ATTR_SONG_LENGTH,
557                         AVRCP_MEDIA_ATTR_TITLE,
558                         AVRCP_MEDIA_ATTR_ARTIST,
559                         AVRCP_MEDIA_ATTR_ALBUM,
560                         AVRCP_MEDIA_ATTR_GENRE
561                     };
562 
563                     uint8_t event[HCI_EVENT_BUFFER_SIZE];
564                     event[0] = HCI_EVENT_AVRCP_META;
565                     pos = 2;
566                     event[pos++] = AVRCP_SUBEVENT_NOW_PLAYING_INFO;
567                     little_endian_store_16(event, pos, connection->avrcp_cid);
568                     pos += 2;
569                     event[pos++] = ctype;
570                     for (i = 0; i < sizeof(attribute_order); i++){
571                         avrcp_media_attribute_id_t attr_id = (avrcp_media_attribute_id_t) attribute_order[i];
572                         uint16_t value_len = 0;
573                         switch (attr_id){
574                             case AVRCP_MEDIA_ATTR_TITLE:
575                             case AVRCP_MEDIA_ATTR_ARTIST:
576                             case AVRCP_MEDIA_ATTR_ALBUM:
577                             case AVRCP_MEDIA_ATTR_GENRE:
578                                 if (items[attr_id-1].value){
579                                     value_len = items[attr_id-1].len <= max_value_len ? items[attr_id-1].len : max_value_len;
580                                 }
581                                 event[pos++] = value_len + 1;
582                                 if (value_len){
583                                     memcpy(event+pos, items[attr_id-1].value, value_len);
584                                     pos += value_len;
585                                 }
586                                 event[pos++] = 0;
587                                 break;
588                             case AVRCP_MEDIA_ATTR_SONG_LENGTH:
589                                 if (items[attr_id-1].value){
590                                     little_endian_store_32(event, pos, btstack_atoi((char *)items[attr_id-1].value));
591                                 } else {
592                                     little_endian_store_32(event, pos, 0);
593                                 }
594                                 pos += 4;
595                                 break;
596                             case AVRCP_MEDIA_ATTR_TRACK:
597                             case AVRCP_MEDIA_ATTR_TOTAL_TRACKS:
598                                 if (items[attr_id-1].value){
599                                     event[pos++] = btstack_atoi((char *)items[attr_id-1].value);
600                                 } else {
601                                     event[pos++] = 0;
602                                 }
603                                 break;
604                             default:
605                                 break;
606                         }
607                     }
608                     event[1] = pos - 2;
609                     // printf_hexdump(event, pos);
610                     (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, pos);
611                     break;
612                 }
613                 default:
614                     break;
615             }
616             break;
617         case AVRCP_CMD_OPCODE_PASS_THROUGH:{
618             // 0x80 | connection->cmd_operands[0]
619             uint8_t operation_id = packet[pos++];
620             switch (connection->state){
621                 case AVCTP_W2_RECEIVE_PRESS_RESPONSE:
622                     if (connection->continuous_fast_forward_cmd){
623                         connection->state = AVCTP_W4_STOP;
624                     } else {
625                         connection->state = AVCTP_W2_SEND_RELEASE_COMMAND;
626                     }
627                     break;
628                 case AVCTP_W2_RECEIVE_RESPONSE:
629                     connection->state = AVCTP_CONNECTION_OPENED;
630                     break;
631                 default:
632                     // check for notifications? move state transition down
633                     // log_info("AVRCP_CMD_OPCODE_PASS_THROUGH state %d\n", connection->state);
634                     break;
635             }
636             if (connection->state == AVCTP_W4_STOP){
637                 avrcp_emit_operation_status(avrcp_controller_context.avrcp_callback, AVRCP_SUBEVENT_OPERATION_START, connection->avrcp_cid, ctype, operation_id);
638             }
639             if (connection->state == AVCTP_CONNECTION_OPENED) {
640                 // RELEASE response
641                 operation_id = operation_id & 0x7F;
642                 avrcp_emit_operation_status(avrcp_controller_context.avrcp_callback, AVRCP_SUBEVENT_OPERATION_COMPLETE, connection->avrcp_cid, ctype, operation_id);
643             }
644             if (connection->state == AVCTP_W2_SEND_RELEASE_COMMAND){
645                 // PRESS response
646                 request_pass_through_release_control_cmd(connection);
647             }
648             break;
649         }
650         default:
651             break;
652     }
653 }
654 
655 static void avrcp_controller_handle_can_send_now(avrcp_connection_t * connection){
656     int i;
657     switch (connection->state){
658         case AVCTP_W2_SEND_PRESS_COMMAND:
659             connection->state = AVCTP_W2_RECEIVE_PRESS_RESPONSE;
660             avrcp_send_cmd(connection->l2cap_signaling_cid, connection);
661             break;
662         case AVCTP_W2_SEND_COMMAND:
663         case AVCTP_W2_SEND_RELEASE_COMMAND:
664             connection->state = AVCTP_W2_RECEIVE_RESPONSE;
665             avrcp_send_cmd(connection->l2cap_signaling_cid, connection);
666             break;
667         case AVCTP_CONNECTION_OPENED:
668             if (connection->notifications_to_register != 0){
669                 for (i = 1; i <= AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED; i++){
670                     if (connection->notifications_to_register & (1<<i)){
671                         connection->notifications_to_register &= ~ (1 << i);
672                         avrcp_prepare_notification(connection, (avrcp_notification_event_id_t) i);
673                         connection->state = AVCTP_W2_RECEIVE_RESPONSE;
674                         avrcp_send_cmd(connection->l2cap_signaling_cid, connection);
675                         return;
676                     }
677                 }
678             }
679             return;
680         default:
681             return;
682     }
683 }
684 
685 static void avrcp_controller_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
686     avrcp_connection_t * connection;
687 
688     switch (packet_type) {
689         case L2CAP_DATA_PACKET:
690             connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_controller_context);
691             if (!connection) break;
692             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
693             break;
694         case HCI_EVENT_PACKET:
695             switch (hci_event_packet_get_type(packet)){
696                 case L2CAP_EVENT_CAN_SEND_NOW:
697                     connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_controller_context);
698                     if (!connection) break;
699                     avrcp_controller_handle_can_send_now(connection);
700                     break;
701             default:
702                 avrcp_packet_handler(packet_type, channel, packet, size, &avrcp_controller_context);
703                 break;
704         }
705         default:
706             break;
707     }
708 }
709 
710 void avrcp_controller_init(void){
711     avrcp_controller_context.role = AVRCP_CONTROLLER;
712     avrcp_controller_context.connections = NULL;
713     avrcp_controller_context.packet_handler = avrcp_controller_packet_handler;
714     l2cap_register_service(&avrcp_controller_packet_handler, BLUETOOTH_PROTOCOL_AVCTP, 0xffff, LEVEL_0);
715 }
716 
717 void avrcp_controller_register_packet_handler(btstack_packet_handler_t callback){
718     if (callback == NULL){
719         log_error("avrcp_register_packet_handler called with NULL callback");
720         return;
721     }
722     avrcp_controller_context.avrcp_callback = callback;
723 }
724 
725 uint8_t avrcp_controller_connect(bd_addr_t bd_addr, uint16_t * avrcp_cid){
726     return avrcp_connect(bd_addr, &avrcp_controller_context, avrcp_cid);
727 }
728 
729 uint8_t avrcp_controller_unit_info(uint16_t avrcp_cid){
730     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
731     if (!connection){
732         log_error("avrcp_unit_info: could not find a connection.");
733         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
734     }
735     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
736     connection->state = AVCTP_W2_SEND_COMMAND;
737 
738     connection->transaction_label++;
739     connection->command_opcode = AVRCP_CMD_OPCODE_UNIT_INFO;
740     connection->command_type = AVRCP_CTYPE_STATUS;
741     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
742     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
743     memset(connection->cmd_operands, 0xFF, connection->cmd_operands_length);
744     connection->cmd_operands_length = 5;
745     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
746     return ERROR_CODE_SUCCESS;
747 }
748 
749 static uint8_t avrcp_controller_get_capabilities(uint16_t avrcp_cid, uint8_t capability_id){
750     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
751     if (!connection){
752         log_error("avrcp_get_capabilities: could not find a connection.");
753         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
754     }
755     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
756     connection->state = AVCTP_W2_SEND_COMMAND;
757 
758     connection->transaction_label++;
759     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
760     connection->command_type = AVRCP_CTYPE_STATUS;
761     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
762     connection->subunit_id = AVRCP_SUBUNIT_ID;
763     big_endian_store_24(connection->cmd_operands, 0, BT_SIG_COMPANY_ID);
764     connection->cmd_operands[3] = AVRCP_PDU_ID_GET_CAPABILITIES; // PDU ID
765     connection->cmd_operands[4] = 0;
766     big_endian_store_16(connection->cmd_operands, 5, 1); // parameter length
767     connection->cmd_operands[7] = capability_id;                  // capability ID
768     connection->cmd_operands_length = 8;
769     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
770     return ERROR_CODE_SUCCESS;
771 }
772 
773 uint8_t avrcp_controller_get_supported_company_ids(uint16_t avrcp_cid){
774     return avrcp_controller_get_capabilities(avrcp_cid, AVRCP_CAPABILITY_ID_COMPANY);
775 }
776 
777 uint8_t avrcp_controller_get_supported_events(uint16_t avrcp_cid){
778     return avrcp_controller_get_capabilities(avrcp_cid, AVRCP_CAPABILITY_ID_EVENT);
779 }
780 
781 
782 uint8_t avrcp_controller_play(uint16_t avrcp_cid){
783     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_PLAY, 0);
784 }
785 
786 uint8_t avrcp_controller_stop(uint16_t avrcp_cid){
787     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_STOP, 0);
788 }
789 
790 uint8_t avrcp_controller_pause(uint16_t avrcp_cid){
791     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_PAUSE, 0);
792 }
793 
794 uint8_t avrcp_controller_forward(uint16_t avrcp_cid){
795     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_FORWARD, 0);
796 }
797 
798 uint8_t avrcp_controller_backward(uint16_t avrcp_cid){
799     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_BACKWARD, 0);
800 }
801 
802 uint8_t avrcp_controller_start_rewind(uint16_t avrcp_cid){
803     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_REWIND, 0);
804 }
805 
806 uint8_t avrcp_controller_volume_up(uint16_t avrcp_cid){
807     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_VOLUME_UP, 0);
808 }
809 
810 uint8_t avrcp_controller_volume_down(uint16_t avrcp_cid){
811     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_VOLUME_DOWN, 0);
812 }
813 
814 uint8_t avrcp_controller_mute(uint16_t avrcp_cid){
815     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_MUTE, 0);
816 }
817 
818 uint8_t avrcp_controller_skip(uint16_t avrcp_cid){
819     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_SKIP, 0);
820 }
821 
822 uint8_t avrcp_controller_stop_rewind(uint16_t avrcp_cid){
823     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
824     if (!connection){
825         log_error("avrcp_stop_rewind: could not find a connection.");
826         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
827     }
828     if (connection->state != AVCTP_W4_STOP) return ERROR_CODE_COMMAND_DISALLOWED;
829     return request_pass_through_release_control_cmd(connection);
830 }
831 
832 uint8_t avrcp_controller_start_fast_forward(uint16_t avrcp_cid){
833     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_FAST_FORWARD, 0);
834 }
835 
836 uint8_t avrcp_controller_fast_forward(uint16_t avrcp_cid){
837     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_FAST_FORWARD, 0);
838 }
839 
840 uint8_t avrcp_controller_rewind(uint16_t avrcp_cid){
841     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_REWIND, 0);
842 }
843 
844 
845 uint8_t avrcp_controller_stop_fast_forward(uint16_t avrcp_cid){
846     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
847     if (!connection){
848         log_error("avrcp_stop_fast_forward: could not find a connection.");
849         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
850     }
851     if (connection->state != AVCTP_W4_STOP) return ERROR_CODE_COMMAND_DISALLOWED;
852     return request_pass_through_release_control_cmd(connection);
853 }
854 
855 uint8_t avrcp_controller_get_play_status(uint16_t avrcp_cid){
856     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
857     if (!connection){
858         log_error("avrcp_get_play_status: could not find a connection.");
859         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
860     }
861     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
862     connection->state = AVCTP_W2_SEND_COMMAND;
863     connection->transaction_label++;
864     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
865     connection->command_type = AVRCP_CTYPE_STATUS;
866     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
867     connection->subunit_id = AVRCP_SUBUNIT_ID;
868     big_endian_store_24(connection->cmd_operands, 0, BT_SIG_COMPANY_ID);
869     connection->cmd_operands[3] = AVRCP_PDU_ID_GET_PLAY_STATUS;
870     connection->cmd_operands[4] = 0;                     // reserved(upper 6) | packet_type -> 0
871     big_endian_store_16(connection->cmd_operands, 5, 0); // parameter length
872     connection->cmd_operands_length = 7;
873     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
874     return ERROR_CODE_SUCCESS;
875 }
876 
877 uint8_t avrcp_controller_enable_notification(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id){
878     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
879     if (!connection){
880         log_error("avrcp_get_play_status: could not find a connection.");
881         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
882     }
883     avrcp_register_notification(connection, event_id);
884     return ERROR_CODE_SUCCESS;
885 }
886 
887 uint8_t avrcp_controller_disable_notification(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id){
888     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
889     if (!connection){
890         log_error("avrcp_get_play_status: could not find a connection.");
891         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
892     }
893     connection->notifications_to_deregister |= (1 << event_id);
894     return ERROR_CODE_SUCCESS;
895 }
896 
897 uint8_t avrcp_controller_get_now_playing_info(uint16_t avrcp_cid){
898     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
899     if (!connection){
900         log_error("avrcp_get_capabilities: could not find a connection.");
901         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
902     }
903     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
904     connection->state = AVCTP_W2_SEND_COMMAND;
905 
906     connection->transaction_label++;
907     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
908     connection->command_type = AVRCP_CTYPE_STATUS;
909     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
910     connection->subunit_id = AVRCP_SUBUNIT_ID;
911     int pos = 0;
912     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
913     pos += 3;
914     connection->cmd_operands[pos++] = AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES; // PDU ID
915     connection->cmd_operands[pos++] = 0;
916 
917     // Parameter Length
918     big_endian_store_16(connection->cmd_operands, pos, 9);
919     pos += 2;
920 
921     // write 8 bytes value
922     memset(connection->cmd_operands + pos, 0, 8); // identifier: PLAYING
923     pos += 8;
924 
925     connection->cmd_operands[pos++] = 0; // attribute count, if 0 get all attributes
926     // every attribute is 4 bytes long
927 
928     connection->cmd_operands_length = pos;
929     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
930     return ERROR_CODE_SUCCESS;
931 }
932 
933 uint8_t avrcp_controller_set_absolute_volume(uint16_t avrcp_cid, uint8_t volume){
934      avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
935     if (!connection){
936         log_error("avrcp_get_capabilities: could not find a connection.");
937         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
938     }
939     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
940     connection->state = AVCTP_W2_SEND_COMMAND;
941 
942     connection->transaction_label++;
943     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
944     connection->command_type = AVRCP_CTYPE_CONTROL;
945     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
946     connection->subunit_id = AVRCP_SUBUNIT_ID;
947     int pos = 0;
948     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
949     pos += 3;
950     connection->cmd_operands[pos++] = AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME; // PDU ID
951     connection->cmd_operands[pos++] = 0;
952 
953     // Parameter Length
954     big_endian_store_16(connection->cmd_operands, pos, 1);
955     pos += 2;
956     connection->cmd_operands[pos++] = volume;
957 
958     connection->cmd_operands_length = pos;
959     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
960     return ERROR_CODE_SUCCESS;
961 }
962 
963 uint8_t avrcp_controller_query_shuffle_and_repeat_modes(uint16_t avrcp_cid){
964     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
965     if (!connection){
966         log_error("avrcp_get_capabilities: could not find a connection.");
967         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
968     }
969     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
970     connection->state = AVCTP_W2_SEND_COMMAND;
971 
972     connection->transaction_label++;
973     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
974     connection->command_type = AVRCP_CTYPE_STATUS;
975     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
976     connection->subunit_id = AVRCP_SUBUNIT_ID;
977     big_endian_store_24(connection->cmd_operands, 0, BT_SIG_COMPANY_ID);
978     connection->cmd_operands[3] = AVRCP_PDU_ID_GetCurrentPlayerApplicationSettingValue; // PDU ID
979     connection->cmd_operands[4] = 0;
980     big_endian_store_16(connection->cmd_operands, 5, 5); // parameter length
981     connection->cmd_operands[7] = 4;                     // NumPlayerApplicationSettingAttributeID
982     // PlayerApplicationSettingAttributeID1 AVRCP Spec, Appendix F, 133
983     connection->cmd_operands[8]  = 0x01;    // equalizer  (1-OFF, 2-ON)
984     connection->cmd_operands[9]  = 0x02;    // repeat     (1-off, 2-single track, 3-all tracks, 4-group repeat)
985     connection->cmd_operands[10] = 0x03;    // shuffle    (1-off, 2-all tracks, 3-group shuffle)
986     connection->cmd_operands[11] = 0x04;    // scan       (1-off, 2-all tracks, 3-group scan)
987     connection->cmd_operands_length = 12;
988     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
989     return ERROR_CODE_SUCCESS;
990 }
991 
992 static uint8_t avrcp_controller_set_current_player_application_setting_value(uint16_t avrcp_cid, uint8_t attr_id, uint8_t attr_value){
993     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
994     if (!connection){
995         log_error("avrcp_get_capabilities: could not find a connection.");
996         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
997     }
998     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
999     connection->state = AVCTP_W2_SEND_COMMAND;
1000 
1001     connection->transaction_label++;
1002     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1003     connection->command_type = AVRCP_CTYPE_CONTROL;
1004     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1005     connection->subunit_id = AVRCP_SUBUNIT_ID;
1006     int pos = 0;
1007     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
1008     pos += 3;
1009     connection->cmd_operands[pos++] = AVRCP_PDU_ID_SetPlayerApplicationSettingValue; // PDU ID
1010     connection->cmd_operands[pos++] = 0;
1011     // Parameter Length
1012     big_endian_store_16(connection->cmd_operands, pos, 3);
1013     pos += 2;
1014     connection->cmd_operands[pos++] = 2;
1015     connection->cmd_operands_length = pos;
1016     connection->cmd_operands[pos++]  = attr_id;
1017     connection->cmd_operands[pos++]  = attr_value;
1018     connection->cmd_operands_length = pos;
1019     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1020     return ERROR_CODE_SUCCESS;
1021 }
1022 
1023 uint8_t avrcp_controller_set_shuffle_mode(uint16_t avrcp_cid, avrcp_shuffle_mode_t mode){
1024     if (mode < AVRCP_SHUFFLE_MODE_OFF || mode > AVRCP_SHUFFLE_MODE_GROUP) return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
1025     return avrcp_controller_set_current_player_application_setting_value(avrcp_cid, 0x03, mode);
1026 }
1027 
1028 uint8_t avrcp_controller_set_repeat_mode(uint16_t avrcp_cid, avrcp_repeat_mode_t mode){
1029     if (mode < AVRCP_REPEAT_MODE_OFF || mode > AVRCP_REPEAT_MODE_GROUP) return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
1030     return avrcp_controller_set_current_player_application_setting_value(avrcp_cid, 0x02, mode);
1031 }
1032 
1033 uint8_t avrcp_controller_disconnect(uint16_t avrcp_cid){
1034     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_controller_context);
1035     if (!connection){
1036         log_error("avrcp_get_capabilities: could not find a connection.");
1037         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1038     }
1039     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1040     l2cap_disconnect(connection->l2cap_signaling_cid, 0);
1041     return ERROR_CODE_SUCCESS;
1042 }